Renal Lab Eval Flashcards
Kidney
- regulates what solutes
- secretes what hormones
- main 5 functions
solutes: sodium, potassium, hydrogen
Hormones: Renin, prostaglandins, bradykinin, EPO, calcium, phosphorus, and 1,25-dihydroxyvitamin D3 or calcitriol
5 Functions:
- regulate production of RBC
- regulates mineral levels
- regulate blood pressure
- regulate acid-base balance
- elimination of metabolic toxins and water through urine
What is Azotemia? Oliguria? Anuria?
Azotemia: elevated BUN and/or Creatinine
*the build up of abnormally large amounts of nitrogenous waste products in the blood.
Oliguria: decreased urine output
- U/O: less than 40oml/day
- U/O: less than 20cc/hr
- normal is 50-100cc/hr
Anuria:
U/O: less than 100ml/day
Differentiating azotemia: describe each..
- pre-renal failure
- intrinsic renal failure
- post renal obstruction
Pre-renal: volume contraction (may be dehydration, isnt actually renal failure)
Intrinsic renal failure: arteriolar damage (acute HTN), glomerulonephritis, Acute tubular necrosis (kidney parenchyma is damaged)
Post renal obstruction: ureteral obstruction, bladder outlet obstruction (kidney parenchyma is okay but there is some type of obstruction, the waste product is filtered just cant be emptied)
GFR
- whats normal for men and women?
- influenced by
- can be measure by
Normal:
- men: 130ml/mn
- women: 120ml/min
Influenced by: age, sex, body size, race
Can be measured by: creatinine clearance, urea clearance, inulin clearance (*gold standard for GFR)
In patients with kidney dz, reduction in GFR……
- either progression in underlying kidney dz or superimposed reversible problem, T/F?
- level of GFR has prognostic indications but is NOT an exact correlate to the loss of nephron mass, T/F?
- stable GFR does not necessarily imply stable dz, T/f?
- some patients w/ renal dz may go unrecognized b/c they have normal GFR, T/F?
they are all TRUE.
BUN
-comes from what?
- when might it be increased? decreased?
- normal range
Urea nitrogen is what is formed when protein breaks down
*when protein is used for energy the carbon is cleaved and nitrogen is left behind and then forms ammonia. Ammonia is processed through the liver to become urea, when urea enters blood stream its called blood urea nitrogen which is then excreted by the kidney.
Increased:
-Renal Dz (failure) **
- excessive protein breakdown
- very high protein diet
- GI bleeding
Decreased:
-liver dz (if liver is unable to convert ammonia to urea then the BUN will decrease and ammonia increases)
-starvation
Normal: 6-20mg/dl
Creatinine Clearance:
- normal values for men and women
- use?
Normal:
-Men: 107-139ml/min
-women: 87-107ml/min
Used to assess GFR
Decreased GFR can lead to increased bun in 2 ways…what are they
- decreased flow through the glomerulus
2. slower transport time allows more BUN to be resorbed at the level of the Proximal Convoluted Tubule
Where does creatinine come from ?
what is normal creatinine for men and women?
50% loss of renal function is needed to increase serum creatine from 1.0 to ___?
creatinine is formed from the normal breakdown of muscle.
Men: 0.8-1.4 mg/dL
Women: 0.6-1.2 mg/dL
2.0mg/dL so, this means creatinine has a very narrow range.
When might creatinine be increased? Decreased?
Increased:
-renal failure
- diet (increased ingestion of meat)
- Meds: ACEi, diuretics, NSAIDS
- Muscle Dz: muscular dystrophy, rhabdo
Decreased:
-pregnancy (normal, 0.4-0.6mg/dL)
BUN Creatinine Ratio
- normal
- elevated
- what causes BUN to be disproportionately increased?
- what causes the BUN/Creat ratio to go up proportionally?
Normal: 10-20:1
Elevated Greater than 20:1
- BUN is disproportionately increased when azotemia is d/t pre-renal causes (such as dehydration)
- if renal dz the BUN/Creat ration should go up proportionally. (this would be intrinisic dz)
What are some examples of Increased (greater than 20:1) BUN w/ normal creatinine?
What are some causes of increased (greater than 20:1) BUN w/ proportionately increased creatinine?
elevated BUN:
- pre-renal dz
- catabolic state w/ increased tissue breakdown
- GI hemorrhage
- High protein intake
- drugs like tetracycline and steroids.
Elevated BUN & Creat:
- Post-renal dz (obstructive uropathy)
- pre-renal dz superimposed on renal dz(intrinsic-renal dz)
What are some examples of decreased ratio (less than 10:1) w/ decreased BUN?
What are some examples of decreased ration (less than 10:1) w/ increased creatinine
Decreased ratio and decreased BUN :
- acute tubular necrosis
- low protein diet, starvation, sever liver dz
- repeated dialysis
- SIADH
- pregnancy
Decreased ratio and increased creatinine:
- rhabdo
- muscular pts who develop renal failure
Regulation of K+
- how do we gain it
- how do we lose it?
- why is it important to be efficient at regulating K+?
- we eat it…50-100mEq daily
- kidneys are main source of K+ loss, 80-90% lost in urine, remainder lost in stool or sweat
- because K+ is all contained within our cells with an exception of 2% in ECF…a small change (1-2%) can lead to dangerously high serum levels!
K+ homeostais is dependent upon…
- pH
- renal function including effects of diuretics, aldosterone, and renal parenchyma
- GI fluid losses
Hypokalemia results from?
Hyperkalemia?
Hypo: K+ shifting to ICF w/o change in total amount of K+ in the body, depletion of body stores.
Hyper:
-acidosis
- cellular damage
- renal/adrenal dz
- medications
Causes of Hypochloremia? Hyperchloremia?
Hypo: GI losses, DKA, mineralcorticoid excess, salt-losing renal dz, high bicarb levels.
Hyper: metabolic acidosis, lower GI losses (diarrhea), mineralocorticoid deficiency
Bicarbonate:
-where is this reabsorbed?
85% reabsorbed in PCT and 15% in DCT
Types of Urine Specimen collection
- Fresh voided urine: first morning specimen, random, or post-prandial specimin
- Clean-catch (midstream)
- Catheterized
- Timed Urine Collection (24hr)
- supra-pubic needle aspiration
WHen collecting urine specimen make sure you…
- record collection time
- mark type of specimen (e.g clean catch)
- analyze it within 2hrs of collection
- free of debris or vaginal secretions
Urinalysis
-three types of examination
physical, chemical, microscropic
Urinalysis:
-physical characteristics
Physical:
- appearance:
- -color (yellow to amber)
- -Turbidity (clear to cloudy)
- -Odor
- Volume:
- -700-2000ml in 24 hrs (1500mL average)
- -Oliguria (less than 400ml/day or less than 20cc/hr)
- -Anuria (less than 100l/day)
Describe the types of odor urine may have, color?
Odor: ammonia like (urea splitting bacteria)
- foul, offensive (pus or inflamm)
- sweet (glucose)
- fruity (ketones)
- maple syrup like (maple syrup urine dz)
Color:
- colorless (dilute)
- deep yellow (concentrated)
- yellow-green (bilirubin)
- red (blood)
- brownish red (acidified blood)
- Brownish black (homogentisic acid(melanin))
What is all looked at in Chemical Urinalysis? What is the quick and dirty way to do chemical urinalysis?
- specific gravity
- pH
- protein
- glucose
- ketones
- bilirubin
- urobilinogen
- blood
- leukocyte esterase
- nitrate
Quick: CLIA waived test, Dipstick (Chemstrip 10, Multistix 10SG)
What is specific gravity measure? When would you see low/ high specific gravity?
degree of concentration or dilution of urine, measures the concentrating abilities of the kidney
- Low SG: Diabetes insipidus
- High SG: DM,CHF
pH of urine is usually what? what is pH of acid or alkaline urine?
What may indicate acidic/alkaline urine?
Urine pH is usually 4.5-8.0
acidic: less than 7
alkaline: greater than 7
Acidic:
-high protein diet, medications, uncontrolled DM
Alkaline:
-diets high in vegetables, milk, dairy, meds, UTI
Urinary Proteins
-what kinds are in the urine?
- Single most important indicator of kidney dz, T/F?
- Causes of Proteinuria: albumin & Bence Jones
- What test is generally used to detect protein?
- what are some benign causes of proteinuria?
Majority are globulins, Tamm-Horsfall mucoprotein
True
Albumin:
-strenuous exercise, pregnancy, glomerulonephritis, infections
Bence Jones: Multiple myeloma, leukemia
Proteinuria detected:
-generally requires 24hr urine collection for total protein. greater than 100mg/24hrs shows up on dipstick
-microalbuminuria not detected on dipstick, need special dipstick test. less than 50mg/dL
Benign Proteinuria:
-high fever, CHF, strenuous exercise, cold exposure
Glucosuria
- when does this occur?
- how much sugar?
- causes of renal glycosuria
Occurs whenever blood glucose level exceeds the renal threshold.
Approximately 180mg/dL
Causes:
- heavy metals
- emotional stress
Ketones:
- ketones in the urine result from what??
- what are the three types of ketones”
- what causes ketonuria?
-result of fatty acid metabolism which occurs when there is inadequate carbs in the diet or there is a defect in carb metabolism
Three Types:
- acetoacetic acid
- acetone
- Betahydroxybutyric acid (78%)**
Cause: DM! (DKA!!!!!) and restricted carb diet (anorexia, GI disturbances, fasting, anesthesia)
Bilirubin:
-do we expect to see this in the urine?
- what causes bilirubinuria:
No, negative urine test is normal.
Cause: hepatocellular dz, biliary obstruction or any dx that increases conjugated bilirubin.
*can be an early indicator of dz, even before jaundice is present.
Urobilinogen
- pathophys
- causes of increased urobilinogen
Patho:
-bilirubin is conjugated in the liver and secreted into bile, bile enters intestinal tract where its converted to urobilinogen, this is then excreted into feces or reabsorbed into portal circulation and removed by the liver and excreted in liver.
Cause:
- pernicious anemia
- liver dz: hepatitis, cirrhosis, CHF
WHat is Hematuria? Hemoglobinuria? What may cause each one?
Hematuria: intact RBC in urine. Caused by renal dz. infections, neoplasm, truama
Hemoglobinuria: free hgb in urine, caused by same things as hematuria plus transfusion rxns, hemolytic anemia, Paroxysmal noturnal hemoglobinuria, severe burns, poisonings
Leukocyte esterase in urine:
- what is this?
- causes
WHat; neutrophilic granulocytes release esterases into the urine when present.
Cause:
- pyuria (WBC in urine)
- bacteriuria/UTI
Nitrite:
- normal in urine?
- causes
no, NitrAtes are normal…NitrItes are not.
Cause:
-bacteriuria
What is the most common nitrate reducing organisms in the urine? What bacteria is NOT known to reduce nitrates?
E.Coli!!!
Strep Faecalis
WHat is frequently seen in Microscopic analysis of urine? describe the subtypes in each type
Frequently seen elements:
- crystals
- cells (RBC, WBC, Epithelial cells)
- infectious agents (bacteria, yeast; candida albicans, parasites; trichomonas, schistomosoma haematobium)
-casts: (RBC; vascular disorder, glomerulonephritis.
WBC; inflamm, acute pyelonephritis, interstitial nephritis, proliferative glomerulonephritis)
Hyaline Casts: transparent empty appearance
Granular Casts: leakage and aggregation of proteins. coarse, deeply pigmented granular casts are characteristic of acute tubular necrosis.
Waxy Casts: last stage in degeneration of granular cast, they are nonspecific and are observed in acute and chronic kidney dz
What may be the onl manifestation of acute glomerulonephritis?
RBC casts!
WHich part of the urinary system would you find each of the following..
- RBC/WBC/Bacterial casts?
- Single RBC/WBC/Bacterial cells?
RBC/WBC/Bacterial casts are coming from the kidney.
Single RBC/WBC/Bacterial cells could be coming from anywhere along the kidney and urinary tract.
